The house rake is obviously only a part of poker's price for fun.
The rest depends on who is playing. Are you better than everyone
else at the table? If the answer is yes, then the price for fun
will usually be zero or less. Poker will pay you money. On the
other hand, if you're the worst player at the table, it is realistic
to expect that nearly every dollar you put into the pot will disappear.
It's like a Sunday golfer playing in a pro tournament. He might
be good with his weekend buddies, but he'll be creamed by the people
who play for a living.

You may not think professionals play in lows takes casino games,
but they do. It's usually young people on their way up or tired
champions on their way down. You'll find semi-professionals who
like to fleece tourists, and eager beginners building a bankroll.
Pro or amateur, the whole mindset is different here than anywhere
else in the casino. These people are serious. It may be fun, but
it's a different kind of fun from spinning the reels on a slot
or throwing dice.

You can have fun, too: just remember that these people want to
take your money. The only way to stop them is to play better or
walk away. If you can't play better, and you're not in the mood
to pay for an education in poker at that moment, then you should
walk. That's always an option. You can fold anytime for any reason.
They can't stop you. Just take your chips and go.

But keep practicing and learning. Eventually it will be you who
is taking the money, stealing pots, and otherwise tweaking noses
with style and aplomb. You'll be the one who can say with confidence
that poker is the ultimate positive expectation games.